Blind bolt and tool combination

ABSTRACT

A blind bolt and tool is used for fastening a bolt through a hole in a structure when only one side of the structure is accessible. A receiver is formed on the tip end of a bolt shaft opposite from a bolt head. Internal threads are formed within the receiver proximate an outward end, and a hex socket is formed in the inward end of the receiver. External threads and a guide are formed on a tip of the tool, and the external threads mate with the internal threads in the receiver to hold the bolt during installation. A hex key on one end of the tool engages the hex socket in the receiver so that the tool may impose a torque on the bolt when a nut is being tightened on the bolt. In another embodiment, a splined tip is formed on the end of the bolt. The tip is designed to shear off when a sufficient torque is applied. Also, a shim is configured to fit between structures held together by the blind bolt.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and makes reference to U.S.non-provisional application Ser. No. 14/734,271, filed Jun. 9, 2015,entitled Blind Bolt And Tool Combination, invented by Michael Strangeand Bruce Carmichael; and U.S. provisional application 62/102,920, filedJan. 13, 2015. Each of the aforementioned applications is incorporatedby reference herein as if fully and completely copied into thisdocument.

FIELD

This invention relates to the field of fasteners and fastener drivetools more particularly, this invention relates to blind bolts and drivetools for torquing blind bolts.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and makes reference to the followingapplications: U.S. non-provisional application Ser. No. 14/705,185,filed May 6, 2015, entitled Step Bolt Connector Assembly, invented byMichael Strange and Bruce A. Carmichael; U.S. non-provisionalapplication Ser. No. 14/727,021, filed Jun. 1, 2015; U.S. provisionalapplication 62/000,225, filed May 15, 2014; U.S. provisional application62/009,357, filed Jun. 9, 2014; U.S. provisional application 62/069,797,filed Oct. 28, 2014; U.S. provisional application 62/079,921, filed Nov.14, 2014; and U.S. provisional application 62/102,920, filed Jan. 13,2015. Each of the aforementioned applications is incorporated byreference herein as if fully and completely copied into this document.

BACKGROUND

Large construction structures often need to be scaled for variouspurposes. For example, large towers are often scaled to change orimprove equipment, modify or reinforce the structure of the tower, andmaintain the tower. In one particular type of tower, the cell phonetower, new innovations and increased demands have created a need to addadditional weight to the cell phone tower. Often, it is necessary ordesirable to reinforce the cell phone tower to accommodate theadditional weight. One technique for reinforcement uses blind bolts.Typically, the blind bolt is used for securing reinforcing the structureor to add additional equipment to the original tower. Of course blindbolts may be used for a variety of different purposes on a variety ofdifferent structures.

A blind bolt is inserted into a hole provided in the structure and thefar end of the bolt is secured within the structure. Some blind boltsmay have an expanding structure on the far end of the bolt that willexpand and prevent the bolt from sliding back through the hole. Theexpanding structure is a “bolt head” as that term is used herein. Thehead of the blind bolt is inserted into a bore terminating at aninaccessible area. A folded washer is inserted through the hole in afolded orientation. On the other side of the hole, the washer isunfolded and placed on the bolt. The washer will then not pass throughthe hole in the structure and the bolt head will not pass through thehole in the washer. Thus, the far end of the blind bolt is securedwithin the structure. Once the far end of the blind bolt is secured, anut is placed on the near end of the blind bolt and the nut is tightenedto secure the blind bolt to the structure. A tool may be provided forholding the blind bolt as the nut is tightened.

While prior bolt and tool hardware has worked reasonably well, a needexists for an easier, faster and more durable blind bolt and toolcombination.

SUMMARY

An improved blind bolt and tool combination is lightweight, fast andsimple to use, and is durable. It is particularly useful for applyingequipment and support structure to a cell tower in demandingenvironments.

In accordance with one embodiment of the present invention, a blind boltand tool is used for fastening a bolt through a hole in a structure whenonly one side of the structure is accessible. A blind bolt is providedwith a bolt head mounted on a bolt shaft, which extends from the bolthead to a tip end of the shaft. Bolt threads are formed on the boltshaft and a receiver is formed on the tip end of the bolt shaft oppositefrom the bolt head. The receiver includes an outward end disposedproximate to the tip end of the bolt shaft. It also includes an inwardend disposed within the bolt shaft toward the bolt head from the tipend. In addition, the blind bolt also includes internal receiver threadsformed proximate the outward end of the receiver; a driven structureformed in the inward end of the receiver, and a plurality of splinesformed on an outer surface of the tip end. These splines are configuredto engage with an inner socket of a tension control wrench. Further thetip end of the bolt shaft is configured to shear away from the bolt whena predetermined amount of torque is applied to the plurality of splineson the tip end.

In accordance with another aspect of the invention, a tool isparticularly designed for holding the bolt while it is inserted througha hole in the structure and for holding the bolt while a nut is beingtightened on the bolt. The tool also applies a torque to the bolt in adirection opposite to the rotation of the nut on the bolt.

The tool includes an elongate body having a forward end and a rearwardend. A tip is formed on the forward end of the elongate tool body, andexternal threads are formed on the tip dimensioned to mate with theinternal threads formed in the receiver. The external threads aredisposed on the rearward end of the tip, which is the end proximate theforward end of the elongate tool body. A key is disposed on the rearwardend of the elongate tool body and is dimensioned and configured to fitwithin the receiver. A drive surface is formed on the key configured tomate with and engage the driven structure in the receiver. The drivesurface and the driven structure interact so that the tool may impose atorque on the bolt through the driven surface of the receiver. In oneembodiment, the driven structure is a hexagon shaped socket and the keyis a hexagon shaped key dimensioned to mate with the socket. It will beunderstood that the key and socket may be other polygon shapes or othershapes so long as the shapes allow a torque to be applied to the bolt bythe key.

In one embodiment the key includes an elongate mounting shaft that ismounted in the center of the elongate tool body. When the key extendsout of the tool body, a bend is provided in the key and a polygon shapedtip extends from the end of the bend. Thus, the polygon shaped tip isdisposed obliquely with respect to the elongate shape of the body. Forexample, the polygon shaped tip may be disposed in a directionsubstantially perpendicular to the elongate shape of the body. Thus, thelength of the body can be used as a lever to apply torque through thereceiver to the bolt.

To facilitate the operation of the tool, a guide is formed on the end ofthe tip. The guide is dimensioned to slide through the internal threadswithin the receiver. The guide then engages the driven structure withinthe inner end of the receiver. Thus, the guide aligns the tool with thebolt before the outer threads on the tip engage the inner threads withinthe receiver. The guide positions the tool so that it easily threads thetip into the receiver without cross threading. The threads on thereceiver and the tip are positioned and dimensioned such that the boltis very quickly mounted on the tool. Once the threads engage, the boltis fully tightened on the tool by a small rotation of the tool relativeto the bolt, preferably less than one full rotation. For example, thebolt may be tightened with a relative rotation of only 180°, one half ofa full rotation.

In operation, the tool and bolt are used by first mounting the bolt onthe tool. The guide is inserted into the receiver and then the bolt isrotated relative to the tool for approximately 180° to thereby tightenand secure the bolt to the tool. The far end of the bolt is theninserted through a hole in a structure while the bolt is still held bythe tip of the tool. Once the bolt is properly positioned within thehole and the far end of the bolt is secured, a washer and a nut areplaced on the near end of the bolt. For example, the washer and the nutmay have been placed on the tool prior to mounting the bolt on the tool.Then, when the bolt is in place the washer slides onto the bolt followedby the nut that is moved from the tool until it engages the bolt. Thenut is then threaded onto the bolt while the tip continues to hold thebolt. At some point, the nut begins to tighten on the bolt and will tendto rotate the bolt in a direction that will unscrew the tool tip fromthe receiver. At such point, the user will unscrew the tip of the toolfrom the receiver and then insert the key into the receiver. The key ismade of a hardened material that is durable and strong. In oneembodiment, the key is disposed at an angle of 90° with respect to thelength of the tool and is disposed on one end of the tool. Thus, whenthe key is inserted into the receiver, the entire length of the tool maybe used as a lever to apply torque to the bolt through the key andreceiver. Using the tool to hold the bolt, the user applies a wrench tothe nut and applies a torque in an opposite direction to the torqueapplied by the tool. After a desired level of torque is applied to thenut, the tool is removed by simply sliding the key out of the socket.

In another aspect, the present disclosure provides a blind bolt assemblyfor fastening a blind bolt in a hole in a structure, wherein only oneside of the structure is accessible. According to one embodiment, theblind bolt assembly includes a blind bolt, a foldable split washer, ashear sleeve, a spring, at least one non-folding washer, and a nut. Theblind bolt, in turn, includes at least a bolt head, a bolt shaftextending from the bolt head to a tip end of the shaft, bolt threadsformed on the bolt shaft, and a receiver formed in the tip end of thebolt shaft—the receiver having an outward end disposed proximate to thetip end of the bolt shaft and having an inward end disposed within thebolt shaft toward the bolt head from the tip end. In addition, the blindbolt also includes receiver threads formed proximate the outward end ofthe receiver; and a driven structure formed in the inward end of thereceiver.

The foldable split washer, the shear sleeve, the spring, and the atleast one non-folding washer are each coaxially disposed about the boltshaft. The nut is threaded onto the bolt shaft. When the blind boltassembly is attached to the structure, the bolt extends through a holein the structure. The bolt head and the foldable split washer aredisposed on an inaccessible side of the structure. At least a portion ofthe shear sleeve and the spring are disposed within the hole in thestructure. Finally, the nut and the at least one non-folding washer aredisposed on an accessible side of the structure.

In certain embodiments of the blind bolt assembly, the at least onenon-folding washer preferably includes a flat washer, a direct tensionindicator washer, and a lock washer.

In certain embodiments of the blind bolt assembly, the shear sleevepreferably includes a spring retainer formed on one end of the shearsleeve. An end of the spring is fastened to the shear sleeve by thespring retainer.

In certain embodiments of the blind bolt assembly, the foldable splitwasher includes first and second semicircular half washers, and eachhalf washer has first and second ends. The foldable split washer alsoincludes a flexible foldable membrane securing the two first endstogether and securing the two second ends together thereby forming thefoldable split washer.

In certain embodiments of the blind bolt assembly, the aforementionedblind bolt also includes a plurality of splines formed on an outersurface of the tip end. These splines are configured to engage with aninner socket of a tension control wrench. Further the tip end of thebolt shaft is configured to shear away from the bolt when apredetermined amount of torque is applied to the plurality of splines onthe tip end.

In accordance with another aspect, the present disclosure provides ashim positioned between a reinforcing plate held to a pole by blindbolts. The shims ensure that the plate remains relatively straight evenif the pole has variations in its surface configuration. The shimincludes a breakaway tab that is held by the user to insert the shiminto place. In addition, the shim includes a slot that is dimensioned toencompass and surround the blind bolt once the shim is inserted fullyinto position behind the plate.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages of the invention are apparent by reference to thedetailed description when considered in conjunction with the figures,which are not to scale so as to more clearly show the details, whereinlike reference numbers indicate like elements throughout the severalviews, and wherein:

FIG. 1 is a side perspective view of a tool used to hold and mount ablind bolt;

FIG. 2 is a perspective enlarged detailed view of the forward end of thetool;

FIG. 3 is a cross-sectional view of the forward end of the tool;

FIG. 4 is an end view of a bolt head;

FIG. 5 is a side view of a blind bolt having a receiver formed in thetip of the bolt;

FIG. 6 is an end view of the tip of the bolt showing the receiver, thebolt and the bolt head;

FIG. 7 is a side perspective view of a shear sleeve configured for usein connection with a blind bolt;

FIG. 8 is a side perspective view of a shear sleeve located on a blindbolt;

FIG. 9 is a cross-sectional view of blind bolt and shear sleeve incombination inserted into a structure having adjacent plates;

FIGS. 10-19 illustrate the process of installing a blind bolt having ashear sleeve into a structure having adjacent plates;

FIGS. 20 & 21 are side perspective views of a blind bolt having splinesadapted for use with a tension control wrench according to oneembodiment of the present disclosure.

FIG. 22a is an isometric drawing of a cell tower pole with areinforcement plate being installed on the pole using a shim;

FIG. 22b is a side elevation view of a cell tower pole with areinforcement plate being installed on the pole using a shim;

FIG. 23 is a somewhat diagrammatic cross-sectional view of a cell towerpole with a reinforcement plate mounted thereon using a blind bolt and ashim; and

FIGS. 24-27 are front perspective views of a reinforcement plate beingmounted on a cell tower pole with a shim being inserted between theplate and the pole such that the shim will surround a blind bolt.

DETAILED DESCRIPTION

Referring now to FIG. 1, a perspective view of the tool 10 is shown. Itis used to mount the blind bolt 40 shown in FIGS. 4-6. A perspectiveenlarged view of one end of the tool is shown in FIG. 2 and across-sectional view taken through line C-C is shown in FIG. 3.Referring collectively to FIGS. 1-3, the tool 10 includes a guide 12formed on the forward end of the tool. The guide 12 includes a roundedpoint 34 and both of these elements will help guide the tool 10 into areceiver of the blind bolt 40.

Toward the base end of the guide 12 and adjacent the forward end 16 ofthe tool 10, threads 14 are disposed on the guide and are used to thesecure the bolt to the tool as well be described hereinafter. Theforward end 16 of the tool 10 is cylindrical in shape and is dimensionedsmaller than the threads of the blind bolt 40. Moving rearwardly fromforward end 16, a triangular portion 18 tapers down to a flat portion 20that is connected to a semi-cylindrical portion 22. These areas of thetool are used to install a folded washer.

The main body of the tool 10 includes a cylindrical mid region 24 thathas a diameter of less than the threads of the blind bolt 40. Thecylindrical mid region 24 extends from a cylindrical rear portion 26having a diameter that is greater than the threaded portion of the blindbolt 40. A handle 28 extends in a direction perpendicular to the rearportion 26, and a hex key 32 is disposed on the rear most end of thetool 10. The hex key 32 includes a shaft (not shown) that extends downthe center of the rear portion 26 and is firmly mounted therein. As thehex key 32 extends away from the rear portion 26, a bend 30 is providedso that the end of the hex key 32 is offset from the center of the tool10 and is oriented in a direction perpendicular to the length of thetool 10.

The entire tool 10 is made from high-tensile steel (for example, 4140steel alloy) suitable for the manufacture of tools and demandingenvironments. The hex key 32 is constructed of a material that is alsohigh-strength and hard. The hex key 32 may be constructed of thematerial that is stronger than the tool 10 because the hex key 32 willbe repeatedly exposed to high torque and wear conditions. Preferably a ⅜inch hex key is used, but other types of keys could be used as well,such as other polygon shapes, flat screw driver sockets, Philips headsockets, etc.

The dimensions of the tool will be described but should not beinterpreted as limiting. The length of the tool 10 from the round tip 34to the rear end of the rear portion 26 is 13.5 inches, and the diameterof mid region 24 is a 0.665 inches. The distance from the tip 34 to therear region 26 is 9 inches. The threads 14 are ½ inch diameter threads(nominal major diameter) at a pitch of 13 threads per inch UNC (coarsethreads). The width of flat member 20 is 0.100 inch. The diameter of theguide 12 is 0.362 inch and its overall length is 0.550 inch. Thesedimensions may change depending upon the application for the tool andthe bolt. Likewise, the dimensions of the bolt will change depending onthe application.

Referring to FIGS. 4-6, a blind bolt 40 is shown that is used with thetool 10 described above. The bolt 40 includes a bolt head 44 with around dome 42. A smooth shaft 46 extends away from the bolt head 44 andtransitions into a threaded shaft 48. On the tip end of the bolt 40, thethreads 48 transition into a smooth cylindrical surface 50 forming thetip end 49 of the bolt 40. A receiver 55 is formed in the tip end 49 andincludes an outward end that is threaded with inner threads 53. Theinward end of the receiver 55 is a polygon socket 52, preferably ahexagon socket 52 having a width from flat to flat of 0.375 inches. Thedepth of the receiver 55, as shown, is 0.590 inches, and the threads 53are ½ inch-13 threads per inch UNC.

Referring to FIG. 6, an end view of the bolt 40 is shown. In this view,lock serrations 54 are shown on the underside of the bolt head 44. Also,it may be seen that the maximum diameter of the hex head 52 is smallerthan the minimum diameter of the threads 53.

In operation, the process of mounting the blind bolt 40 through a holeto a structure begins by mounting nuts and washers on the mid region 24.Applying these items from the tip 12, a nut 64 is first placed on thetool 10, then a solid washer 66, and finally a folded washer 68 isplaced on the tool 10. The nut 64 and the solid washer 66 are disposedon the mid region 24 adjacent to the rear region 26. The folded washer68 is mounted on the regions 20 and 22 of the tool 10. Next, the tip 12is inserted into the receiver 55. The tip 12 is dimensioned to fitwithin the hex socket 52. The rounded point 34 helps provide an initialalignment of the tip 12 with the receiver 55. As the tip 12 continues tomove forward it begins to align the tool 10 as it passes through thethreads 53. When the tip 12 enters the hex socket 52, it fits snugly,and thus the interaction between the tip 12 and the hex socket 52quickly and precisely aligns the tool 10 with the bolt 40. When thethreads 14 engage the threads 53, the tool and the bolt are alreadyaligned and it would be difficult if not impossible to cross thread thethreads 14 and 53. With approximately a one half turn of the tool 10,the threads 14 and 53 tighten and secure the bolt 40 to the tool 10.

With the bolt 40 mounted on the tool 10 a user is ready to begin theprocess of inserting the bolt 40 into a structure 70, as shown generallyin FIGS. 10-19. First, the bolt head 44 is passed through a hole 72 inthe structure 70. The tool 10 is continued forward until a folded washer68 disposed on the regions 20 and 22 is pushed completely through thehole 72. Then the folded washer 68 is unfolded and the bolt head 44 ismoved against the folded washer 68 to pinch the washer against an insidesurface of the structure 70. Thus, the bolt head 44 is captured withinthe structure. At this point, a washer 66 and nut 64 are moved from thetool 10 onto the threaded shaft 48. As the nut 64 is tightened on theshaft 48 eventually it will tighten to a point where the bolt will tendto rotate. Doing so will unscrew the threads 14 and 33. Once thesethreads are loosened, the tool 10 is quickly removed from the bolt 40and the hex key 32 is inserted into the hex socket 52. In thisconfiguration, the entire length of the tool 10 may be used as a leverto apply a torque to the bolt 40 while the nut 64 is tightened on thethreaded shaft 48 with a wrench. Once a sufficient force or torque hasbeen applied to the nut 64, the hex key 32 is removed from the hexsocket 52 and the process is complete.

From the above discussion, it will be appreciated that the disclosedtool 10 is fast, durable, lightweight, easy to operate and strong. Theguide tip 34 makes it easy for the user to place the bolt 40 on the tool10 and create proper alignment. The coarse threads on the tool 10 andthe bolt 40 make it quick and easy to securely join the bolt 40 to thetool 10. The hex key 32 and hex socket 52 allow the tool 10 to bereconnected to the bolt 40 in six different positions or orientationsand allows the overall length of the tool 10 to be used as a lever whenapplying torque to the bolt 40. These advantages are most useful indemanding environments. For example a worker at high elevations on acell tower may conveniently use the tool 10 and bolt 40 to secureequipment and structures to the tower.

Now, with reference to FIG. 7, in certain embodiments, the tool 10 maybe provided with a bolt 40 having a sleeve 60 and a spring 62. Thespring 62 may be spot welded, glued or otherwise adhesively secured tothe sleeve 60. In some embodiments the spring 62 may be separate fromthe sleeve 60, but positioned to perform the same function as describedbelow. For example, in an alternative embodiment, one end of the shearsleeve 60 may include a flange 74 or other similar structure whichfunctions as a spring retainer. An end of the spring 62 is fitted overthis flange 74 so that the spring is thereby fastened to the shearsleeve 60 by the flange 74, without the need for welds, glues, or otheradhesives.

The metallic sleeve 60 and spring 62 are preferably galvanized, powdercoated or otherwise made rust proof. In combination, the sleeve 60 andspring 62 form a spring-loaded shear sleeve that may be used to protectthe bolt 40 against sheer forces present when adjacent plates of thestructure 70 shift with respect to one another. The spring 62 acts as aspring positioner because it positions the sleeve 60 within a bore orhole at the seam or interface of two plates. As shown in FIGS. 8 and 9,the sleeve 60 and spring 62 may be inserted onto the blind bolt betweenthe folded washer 68 and the solid washer 66. Preferably, the spring 62and sleeve 60 are sized so that they contact the inward facing surfacesof the folded and solid washers 66, 68. The inside diameter of thesleeve 60 and spring 68 are sized slightly larger than the outerdiameter of the threads of the blind bolt 40 so that the sleeve 60 andspring 68 slide easily onto the bolt 40.

As shown best in FIG. 9, when a bolt 40 is inserted into a structure 70having adjacent plates P, one plate may sometimes shift position withrespect to the other plate, thereby causing a shearing force. Thisshearing force may cause the bolt 40 to be damaged or to fail entirely.Accordingly, the spring-loaded shear sleeve acts to protect the bolt 40against these shear forces. In particular, the sleeve 60 is configuredto surround the bolt 40 and to straddle the intersection between the twoadjacent plates P.

If a sleeve 60 were placed over the bolt 40 by itself, it may not becorrectly located within the hole or bore (i.e., straddling theintersection of the plates) to protect the bolt 40. One reason for thisis that the sleeve 60 might slide to the opposite end of the bolt 40where it no longer straddles the intersection. One reason that thesleeve 60 may not be correctly positioned is that the thickness ofplates may vary from one application to the next and, for thicker platesthe sleeve might slide to the opposite end of the bolt where it nolonger straddles the intersection. For this reason, the spring 62contacts one washer and causes the sleeve 60 to be pressed against theopposite washer. As long as the sleeve 60 is sufficiently long to extendfrom the inside of that washer to the intersection, it will beautomatically located in the correct location when the spring 62 andsleeve are compressed between the washers 66, 68.

FIG. 9 further illustrates the use of a squirter washer 76 (sometimesreferred to as a direct tension indicator washer) in connection with ablind bolt 40 and sleeve and spring. The squirter washer 76 includesembedded silicone that squirts out of the washer when the desire amountof torque is applied to the washer 76.

With further reference to FIGS. 8 and 9, the overall blind bolt assembly80 for fastening a blind bolt 40 in a hole 72 in a structure 70 havingonly one accessible side may be seen. The overall assembly 80 includesthe blind bolt 40, a foldable split washer 68, a shear sleeve 60, aspring 62, a flat washer 66, a direct tension indicator washer 76 and anut 64. The assembly may also optionally include a lock washer. Each ofthe washers 66, 68, 76, the shear sleeve 60, and the spring 62 arecoaxially disposed about the bolt shaft 46. A portion of the flat washer66 and folded washer 68 may extend partially into the hole 72 in thestructure 70 in order to center the washers on the bolt 40 and withinthe hole. The nut 64 is threaded onto the bolt shaft 46. As seen in FIG.9, when the blind bolt assembly 80 is attached to the structure 70, thebolt 40 extends through a hole in the structure. The bolt head 44 andthe foldable split washer 68 are disposed on an inaccessible side of thestructure. At least a portion of the shear sleeve 60 and the spring 62are disposed within the hole in the structure. Finally, the nut 64 andthe at least one non-folding washer are disposed on an accessible sideof the structure 70.

FIGS. 10-19 illustrate one embodiment of a blind bolt 40 including aspring positioner being inserted into a structure in the mannerdescribed above. As seen in FIGS. 10 and 11, a blind bolt 40, along withother components of the blind bolt assembly 80 are attached to the tool10. The spring 62 and shear sleeve 60 are then positioned on the tool10. The foldable split washer 68 is also folded and positioned on thetool 10, as may be seen in FIGS. 12-14. The bolt 40 is then insertedinto a hole 72 in the structure 70. First, the bolt head 44 is passedthrough the hole 72, as shown in FIG. 15. The tool 10 is continuedforward until a folded washer 68 disposed on the regions 20 and 22(FIG. 1) is pushed completely through the hole 72, as seen in FIG. 16.Then, the folded washer 68 is unfolded and the bolt head 44 is movedagainst the folded washer 68 to pinch the washer against the structure70. The shear sleeve 60 and spring 62 are also inserted into the hole72, as shown in FIG. 17. Lastly, the non-folding washers 66, 76 aremoved from the tool 10 onto the bolt 40, as shown in FIG. 18, and thenut 64 is threaded onto the bolt and tightened as shown in FIG. 19.

In an alternative embodiment of the present disclosure, a blind bolt 140adapted for tightening using a tension control wrench instead of the hexwrench discussed previously may be used. Similar to the blind bolt 40discussed above, and as shown in FIGS. 20 and 21, the blind bolt 140includes a bolt head, a bolt shaft extending from the bolt head to a tipend 149 of the shaft, bolt threads 148 formed on the bolt shaft, and areceiver 155 formed in the tip end of the bolt shaft. The receiver 155has an outward end disposed proximate to the tip end 149 of the boltshaft and an inward end disposed within the bolt shaft toward the bolthead from the tip end. In addition, the blind bolt 140 also includesreceiver threads formed proximate the outward end of the receiver 155and a driven structure formed in the inward end of the receiver. Inaddition, according this embodiment, the blind bolt 140 also includes aplurality of splines 182 formed on an outer surface of the tip end 149,which are configured to engage with an inner socket of a tension controlwrench. Moreover, the tip end 149 of the bolt shaft is configured tobreak or shear away from the bolt 140 when a predetermined amount oftorque is applied to the plurality of splines 182 on the tip end 149, asseen in FIG. 21.

Thus, the final tightening of the nut on the blind bolt 140 may beaccomplished using a tension control wrench, which includes both aninner socket which engages with the splines 182 of the tip end 149 andan outer socket which engages nut threaded onto the bolt. A torque isapplied to the nut by the outer socket while the inner socket holds thesplines 182 of the tip end 149 stationary, or applies an oppositetorque, thus tightening the nut on the blind bolt. When a predeterminedamount of torque is applied, the tip end 149 of the bolt 140 shaft willshear away from the bolt. In this manner, a plurality of blind bolts andnuts may be tightened to a more consistent and uniform torque.

In a variation of the above embodiment, the nut may be tightened on theblind bolt without breaking away the tip end 149. In this variation, atension control wrench is used that slips when a predetermined amount oftorque is applied between the inner socket and the outer socket. Whenthe nut is tightened, the tension control wrench applies a torque to thenut using the outer socket and applies an opposite torque to the splinedtip end 149 with the inner socket. The applied torque will increaseuntil the predetermined amount of torque is applied between the innerand outer sockets. Then, the wrench will begin to slip and will notincrease the amount of torque. Thus, a predetermined torque is appliedto the nut, and assuming the predetermined amount of torque is less thanthe breakaway torque of the tip, the tip will not be sheared away by thetension control wrench. In this embodiment, the blind bolt could beremoved by using the tension control wrench to apply opposite torquesusing the inner and outer sockets. Thus, theoretically, the blind boltcould be easily removed, inspected and reused or replaced. However, oneadvantage of the breakaway tip would be lost. When a blind bolt isobserved with the tip broken away, an inspector can be assured that theproper torque was applied to the nut when the bolt was installed. If thetip is not broken away, an inspector loses that assurance.

Referring now to FIGS. 22a and 22b , there is shown two views of areinforcement plate 202 mounted on a pole 200 illustrating anotheraspect of the present invention. FIG. 23a is an isometricthree-dimensional view, and FIG. 23b is a somewhat diagrammatic sideelevation, cross sectional view. The reinforcing plate 202 is held tothe pole 200 by blind bolts 204, and a shim 208 is positioned betweenthe plate 202 and the pole 200 to ensure that the plate 202 remainsrelatively straight even if the pole 200 has variations in its surfaceconfiguration. The shim 208 includes a breakaway tab 210 that is held bythe user to insert the shim 208 into place. In addition, the shim 208includes a slot 212 that is dimensioned to encompass and surround theblind bolt 204 once the shim is inserted fully into position behind theplate 202.

As best shown in FIG. 23, the pole 200 is constructed in two parts,namely, pole 200 a and pole 200 b. Pole 200 a is disposed on theexterior of pole 200 b and thus the poles 200 a and 200 b have aslightly different diameter. The outside diameter of 200 a is equal tothe inside diameter of 200 b, and thus there is a surface irregularityat the intersection 200 c of the two poles 200 a and 200 b. Because ofthe surface irregularity at the intersection 200 c, a gap 206 is formedbetween the plate 202 and the pole 200 b. To maintain the straight shapeof the plate 202, a shim 208 is placed into the gap 206. By using theshim 208 in one or more gaps between the plate 202 and the pole 200 b,the appearance of a straight reinforcing plate 202 is created. Inreality, the reinforcing plate must bend slightly to conform to theoverall shape of the pole 200, but the shims create a gradual bend inthe plate 202 which is less objectionable. Thus, the plate 202 willappear straight or less wavy than would otherwise be possible withoutthe shims 208.

A cross-sectional view of the blind bolt 204 utilizing the shim 208 isshown in FIG. 23. In this view, it may be appreciated that the blindbolt 204 is assembled in a manner previously described with respect toprior embodiments with a folded washer 68 disposed on the interior ofthe pole 200 a and a solid washer 66 disposed on the bolt 204 on theexterior side of the plate 202. A nut 64 is threaded onto the bolt 200to hold the entire assembly in place. In this view, the sheer sleeve 60is disposed at the intersection of the plates 200 a and 200 b and at theintersection of plate 200 a and the reinforcing plate 202, and thus thesheer sleeve 60 will resist and absorb shear forces between the variousstructures at the aforementioned intersections. In particular, any shearmovement of the plate 202 with respect to the pole 200 a will beresisted by the sheer sleeve 60. The spring 62 will initially positionthe sheer sleeve 60 into a proper position for resisting shear forces,and it will hold the sheer sleeve 60 in proper position throughout thelife of the structure.

In this view, it may be appreciated that the shim 208 occupies a gap 206that is formed between the reinforcing plate 202 and the pole 200 b.Without the shim 208, the bolt 204 would tend to bend the reinforcingplate 202 slightly at the point of intersection 200 c between the poles200 a and 200 b. It addition, more bolts 204 would be placed through thepole 200 b and the plate 202 at positions below the bolt 204 shown inFIG. 23. Each additional bolt 204 through the gap 206 will also beplaced with a shim 208 in the gap 206 so that the pressure applied bythe bolts will not tend to bend the reinforcing plate 202 and create awavy or bent shape. The shims 208 will allow the plate 202 to graduallyconform to the overall shape of the pole 200 without giving theappearance of being wavy or bent.

In FIGS. 24-27 the shim 208 is being installed on the exterior surfaceof a pole 200 a adjacent to the interior of a reinforcement plate 202.In these views, the tip end 149 of the blind bolt 204 is visible withthe nut 64 securing the bolt 204 to the plate 202. In FIG. 24, the shim208 is shown immediately after its left edge is first inserted beneaththe plate 202 in the gap 206 shown in previous drawings. The slot 212 isaligned with the bolt 204 so that the slot 212 will slide over andencompass the bolt as previously described. In FIG. 25, the shim 208 hasbeen moved to the left and the slot 212 has now begun to encompass thebolt 204. The shim 208 is held in position by a user who is grasping thetab 210. In FIG. 26, the shim 208 has been completely inserted behindthe plate 202 and only the tab 210 remains visible. When the plate is inthe position shown in FIG. 26, the nut 64 is tightened at least enoughto firmly secure the shim 208 in place. Then, the tab 210 is bentforward and back to weaken the metal attaching the tab 210 to the shim208 until it breaks cleanly in a line formed by the right-hand edge ofthe shim 208. As will be described hereafter, the tab 210 includes aweakened structure extending along a line defined by the edge of theshim 208. This weakened structure may be a score or a crease. After thetab 210 is moved forward and backwards until it breaks, the shim 208will be firmly secured in position behind the plate 202 with no portionof the shim being visible in the plan views shown in FIG. 27.

The shim 208 may be constructed in different sizes and differentthicknesses depending upon the particular application. The dimensions ofvarious exemplary shims 208 will be described but should not beinterpreted as limiting. The shims 208 are generally square in shape andmay have dimensions ranging from 4 by 4 inches to 8.5 by 8.5 inches. Theslot 212 of the shims 208 has an opening width of about 1.118 inches anda depth that ranges from about 2.59375 inches to about 4.84375 inches.The tabs 210 of the shims 208 are approximately 1.188 inches wide andabout 1.188 inches to about 2.188 inches long. Larger shims 208preferably have larger tabs 210. In the embodiment shown in FIGS. 24-27,the shim 208 has a thickness of about 1/16 inch, but the shims may havea variety of thicknesses depending upon a particular application. Thematerial of the shims 208 may also change depending upon theapplication. In the case of a cell tower application, the preferredmaterial is galvanized steel. However, the shims may also be constructedof brass, copper, aluminum, stainless steel, rust resistant steel andother metals. In some applications, nonconductive nonmetallic materialsmay be preferred such as nylon, polyester, polypropylene, otherpolymers, rubber and synthetic rubber.

A particularly useful feature of the shim 208 is a weakened structure214, which is disposed along a line that is co-linear with the rightedge of the shim 208 as shown in FIGS. 24 and 25. The weakened structure214 may be a score, a crease, a crimp, perforations or some otherweakening structure. The weakened structure 214 assists in the removalof the tab 210 once the shim 208 is properly held in place bycompression between plates, for example. When the tab 210 is movedforward and backwards along a line of rotation through the weakenedstructure 214, fatigue rapidly causes the tab to break away from theshim 208. Thus, the tab 210 functions to assist the user in holding andpositioning the shim 208 during installation and then easily breaks awayso that the exterior appearance of the overall structure remainspleasing and uncluttered.

The foregoing description of preferred embodiments for this inventionhas been presented for purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Obvious modifications or variations are possible inlight of the above teachings. The embodiments are chosen and describedin an effort to provide the best illustrations of the principles of theinvention and its practical application, and to thereby enable one ofordinary skill in the art to utilize the invention in variousembodiments and with various modifications as are suited to theparticular use contemplated. All such modifications and variations arewithin the scope of the invention as determined by the appended claimswhen interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

What is claimed is:
 1. A blind bolt for extending through a cylindricalhole, the hole having a diameter and a length, the hole extendingthrough a first metal member and second metal member with a surfaceformed on the second member adjacent the hole, the blind boltcomprising: a blind bolt head having a diameter that is smaller than thediameter of the hole; a threaded blind bolt shaft extending from theblind bolt head and having a length greater than the length of the hole;a folding washer being foldable along a fold line and being disposed onthe bolt shaft between the bolt head and the surface on the secondmember and contacting the surface along substantially all of acircumference of the hole except along the fold line, the folding washerhaving a folded configuration with a diameter smaller than the diameterof the hole and configured such that it may pass through the hole andhaving an unfolded configuration with a diameter greater than thediameter of the hole and configured such that it may not pass throughthe hole; a shear sleeve disposed on the blind bolt shaft proximate thefolding washer and having a length dimension sufficient to extend fromthe washer, through the second metal member and into the first metalmember; a spring disposed on the blind bolt shaft adjacent to the shearsleeve; a washer disposed on the blind bolt shaft adjacent to the springand adjacent to the first member; a nut threaded on the blind bolt shaftadjacent to the washer, the spring and the shear sleeve having acombined length that is greater than the length of the hole so that whenthe sleeve and spring are positioned within the hole and the nut istightened, the spring is in compression.
 2. A blind bolt comprising: ablind bolt head having a diameter; a threaded blind bolt shaft extendingfrom the blind bolt head to a blind bolt tip; a folding washer having afolded configuration and an unfolded configuration and folding along afold line, the folding washer having a hole in the unfoldedconfiguration, the hole being sized to fit around the bolt shaft, thefolding washer being disposed in an unfolded configuration on the boltshaft adjacent the bolt head, a washer disposed on the blind bolt shaft;a shear sleeve and a spring disposed on the blind bolt shaft between thewasher and the folding washer, the shear sleeve having an end engagingan end of the spring such that the spring may be compressed against theshear sleeve by the washer and folding washer to thereby position theshear sleeve on the bolt; and a nut threaded on the blind bolt shaftadjacent to the washer such that the nut may be tightened to compressthe shear sleeve and spring between the washer and folded washer.
 3. Theblind bolt of claim 2 wherein the shear sleeve is positioned adjacentthe folded washer in the unfolded configuration on the blind bolt shaft.4. A method for reinforcing a tower having a wall with a thickness,comprising: providing a blind bolt, the blind bolt comprising: a blindbolt head having a diameter; a threaded blind bolt shaft extending fromthe blind bolt head to a blind bolt tip; a folding washer having afolded configuration and an unfolded configuration, the folding washerhaving a hole in the unfolded configuration sized to fit around the boltshaft, the folding washer being disposed in an unfolded configuration onthe bolt shaft adjacent the bolt head, a washer disposed on the blindbolt shaft; a shear sleeve and a spring disposed on the blind bolt shaftbetween the washer and the folding washer, an end of the shear sleeveengaging an end of the spring such that the spring may be compressedagainst the shear sleeve by the washer and folding washer to therebyposition the shear sleeve on the bolt; and a nut threaded on the blindbolt shaft adjacent to the washer such that the nut may be tightened tocompress the shear sleeve and spring between the washer and foldedwasher; attaching the blind bolt tip to a tool; moving the foldingwasher, shear sleeve, spring, washer and nut from the blind bolt shaftto the tool; providing a reinforcing plate adjacent a wall of the towerand providing a hole extending through the reinforcing plate and thewall of the tower; inserting the blind bolt and the washer through thehole using the tool; unfolding the washer and positioning the unfoldedwasher adjacent the wall using the tool; moving the shear sleeve andspring into the hole; moving the washer and nut onto the blind boltshaft and tightening the nut against the washer and the reinforcingmember; providing the spring and the shear sleeve with a combined lengthgreater than the length of the hole through the wall and the reinforcingplate so that the spring is compressed when the nut is tightened and thespring forces the shear sleeve into a position on the blind bolt shaftwithin the hole; removing the tool from the tip of the blind bolt shaft.5. The method of claim 4 wherein the step of tightening the nutcomprises tightening the nut while the tool is attached to the tip andfurther tightening the nut to a desired torque after the tool is removedfrom the tip.
 6. The method of claim 4 wherein the first step ofproviding the blind bolt further comprises providing the blind bolt withthe shear sleeve positioned on the blind bolt shaft adjacent to thefolded washer.